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Flashcards in Time Deck (48):
1

The basic unit of time is known as the ..... ..... .....

mean solar day

2

A solar day doesnt quite correspond to .....

a solar day becasuse the earth moves forward as it rotates

3

Since the speed of the earths rotation varies so does the ......

length of a mean solar day throughout the year

4

Time measured at a meridian is reffered to as 

LMT

5

Because all meridians are different we work time into ..... .....

time zones

6

Eastern Australia uses the ..... meridian

1500E

7

Central Australia including Broken Hill uses the ..... meridian

142030'E

8

Western Australia uses the ..... meridian

1200E

9

The earth rotates 3600 per day so it travels ..... per hour

150

10

Define how to work out how many hours from UTC a meridian is 

Take the meridians location eg 1500

Divide the meridian by 40

this will give you the hours ahead or behind UTC

EG

1500E / 150ph = 10 hours ahead of UTC

11

Converting a meridians location to hours is known as ....

Arc to Time Conversion

12

In aviation how big is the date time group?

usually just 6 figures since the year and month are said to be understood

13

BOD / EOD

Define 'Civil Twilight'

it is the time before sunrise and after sunset when the sun is within 60 of the observers horizon

14

Define 'Astronomical Twilight'

this extends to 180 below the observers horizon

15

BOD commences when .....

at the commencement of civil twilight

16

EOD occurs at the end of .....

civil twilight

17

at latitudes other than the equator the suns apparent path is .....

inclined from the vertical angle equal to the observers latitude and is never exactly overhead

18

Twilight

The inclination of the suns apparent path at ..... ..... means that it has to travel a ...... ..... and takes ......

higher latitudes means that it has to travel a greater distance and takes longer

19

Twilight

At the equator the duration of twilight is .... .... and darkness follows about ..... ....

very short and darkness follows about 10 minutes after sunset

20

In the southern hemispher:

In summer the sun rises .... .....

In winter the sun rises .... ....

At the equinox .....

Summer = further south of east

Winter = Further north of east

At the equinox it is exactly in the east but never exactly overhead because of the latitude

21

Because the earth tilts toward and away from the sun during the various seasons the BOD and EOD will occur at ..... LMTs for the same locations on different dates

different

22

also because of the earths tilt BOD and EOD may be ..... for different locations on the ..... .....

different for different locations on the same date

23

The winter solstice is the .... ..... of the year and occurs around ......

shortest day of the year and occurs around the 20th or 21st of June

24

The summer solstace is the ...... day of the year and occurs around the ...... 

longest day of the year and occurs around the 21st or 22nd of December

25

Which days caus the greatest variation of BOD and EOD for different locations/

the solstice

26

The spring and Autum equinox occur .....

spring = September 22nd or 23rd

Autumn March 20th 21st

27

During the spring and autumn equinox what happens to the days and nights?

They are of equal length and every location on earth experiences the BOD and EOD at the same LMT

28

Why dont the solstice's occur at the same date each year?

It is because there is not an exact whole number of days in a year because of the earths orbit around the sun.

29

On the BOD and EOD graph the point where all the lines converge is known as the .....

Equinox and represents the time when BOD and EOD is the same everywhere

30

On the BOD and EOD graphs the greatest seperation in lines means ......

The time when the solistace is occuring

31

Describe the matrix to find BOD ......

1. Find the date

2. Find the latitude

3. Note the LMT

4. Convert the longitude - Arc to time 

5. Subtract the Arc to Time conversion from LMT

6. You have UTC

7. Convert the UTC to LMT by adding EST, CST or WST

32

During winter in the southern hemispher the LMT of EOD would occur earlier at the destination than at the departure point for a flight which travels .....

South

33

The duration of daylight experienced by the occupants of an aircraft is less than experienced at the departure point for a flight which travels .....

East

34

For a flight which travels south in the southern hemisphere on the autumn equinox the LMT of EOD would occur at .... ..... ..... at the ..... as the ..... .....

the same time at the destination as the departure point

at the equinox the EOD and BOD is the same at all latitudes

35

Places on the same meridian will always have te same LMT for BOD on any given day

T/F

False

this only occus at the equinox

36

Places on the same parallel of latitude will always have the same LMT for BOD on any given day

T/F

True

The only factors that determin the BOD are latitude and date

37

The longest night of the year occurs at .....

the winter solistace

38

The LMT of BOD would be earlier at the destination than at the departure point in the southern hemisphere for a flight which travels .....

south in summer

If the LMT of BOD gets earlier the days are getting longer. This occurs as you travel south in the summer

39

Morning civil twilight commences when .....

the sun is 60 below the horizon

40

The duration of the periof of twilight .....

increases as latitudes increase

41

The longest day of the year is the ....

summer solistace

42

The passengers and crew of a flight which travels east on a given date will experience ..... hours of daylight than the people at the .....

fewer hours of daylight than the people at the departure point and the destination

43

The time taken to cross 2 consecutive meridians is .....

4 minutes

The earths rotates 3600 in 24-hours. That's 150 every hour. 150 into 60 minutes = 4 minutes per degree.

44

As you fly south in winter the days get .....

shorter

45

As days get shorter the EOD would be sooner in Sydney/Cairns and therefore later in Sydney/Cairns

Sydney then cairns

46

A day VFR flight should not depart if the planned ETA at the destination is later than .....

10 minutes before the EOD

AIPENR 1.2.1

47

The occupants of an aircraft will experience more hours of daylight than the people at the departure point or destination if the aircraft travels .....

west

48

On the date of the spring equinox BOD and EOD will occur at .....

the same time for observers on the same meridian

every location on earthe will experience the EOD and BOD at the same time!